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Geology

20,000 years of volcanic history is waiting to be discovered.

Mangere Mountain is one of the peaks that make up the Auckland Volcanic Field. Within that large volcanic zone it is part of a sub-group of volcanoes including Puketutu Island, Mangere Lagoon and Pukaki.

At 106 metres above sea level, Mangere Mountain is the best-preserved volcanic cone in the area and one of the largest scoria cones in the Auckland area. It first erupted around 20,000 years ago. Lava fields spread out in all directions except the southeast, covering around five square kilometres.

The sequence of events probably began with a bubble of magma forcing its way up through the crust. Upon coming into contact with ground water, violent explosions would have led to the creation of a tuff ring. Fire fountaining then followed, with lava bombs blasting up into the air and forming steep mounds. Semi-liquid lava emerged, flowing from a breech in the crater and forming a tholoid (plug) in the middle of the main crater.

But the eruption wasn’t over yet. New vents blasted out more scoria, and one of them became so large it formed a second, very steep crater.

Today our mountain sits peacefully in the landscape. The volcanic activity that formed it has long since died away – but you can see its evidence all around you.